Add unpublishExtension to GalleryApi

[damccorm]

Consider adding unpublishExtension to the GalleryApi (probably requires some work on the generation side).

See here

[damccorm]

@joaomoreno does an endpoint exist for unpublishExtension? Or does it exist under a similar name? I wasn't able to find one and we would need that before we can generate it here.

[damccorm]

Closing after offline discussion - this can be achieved using updateExtensionProperties

[nschonni]

Nice! Is there a work item to get this documented somewhere?